A SENSITIVE METHOD FOR NAPHTHALENE OXYGENASE ASSAY IN WHOLE CELLS

The naphthalene oxygenase activities of strains degrading this compoun d are frequently low. Spectrometric methods allow determination only d own to a minimum of 10 nmol/min/mg protein. Difficulties also result f rom the fact that the measurements mostly require whole cells, which i nvolves a high background signal. We developed a new sensitive method which enables high cell concentrations to be used because the naphthal ene is determined after extraction from the reaction mixture with cycl ohexane. This approach has other advantages which are discussed. The m ethod was applied to different strains which degrade naphthalene at va rying rates and to a community. The values determined coincided with t hose calculated from the rate of oxygen consumption.